Gateway digital loop carrier device

ABSTRACT

A gateway digital loop carrier device accommodates an integrated access device accommodating as a subscriber at least one of a telephone, a modem and ISDN and implementing a TR-008 interface, executes an interface conversion between TR-008 and TR/GR-303, and connects the subscriber to a switch implementing a TR-303 or GR-303 interface.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.09/960,096 filed on Sep. 21, 2001, now pending, and claims priority fromJapanese Application Number 2001-136142, filed on May 7, 2001, thecontents of which are herein incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a gateway digital loop carrier deviceprovided between an integrated access device and a switch that haveinterfaces different from each other.

FIGS. 11A and 11B are diagrams showing a conventional subscriberoriented network. Referring to FIGS. 11A and 11B, a remote digitalterminal (RDT) is connected to a local switch (Central Office (CO)) viaa digital transmission facility such as optical fibers and so on.

The remote digital terminal is located farther than the central officeand accommodates subscriber terminals such as telephones etc. thatcannot be accommodated directly in the central office in terms of aproblem of distance. The remote digital terminal is based on Telcordia(previously called Bellcore) TR-008 defined as one of the switchinterface (interconnection interface) standards (the remote digitalterminal based on TR-008 will hereinafter be referred to as “TR-008RDT”as the case may be). On the other hand, the switch is also based onTR-008.

The TR-008RDT converts signals on 96 telephone subscriber lines at themaximum into digital signals DS0s (Digital Signal level 0). Then, theTR-008RDT clusters the converted signals DS0 for every 24 subscribers,multiplexes these signals into four lines (five lines including aprotection line) of DSX-1 or T1 signals (DS1) at the maximum, andcarries the DSX-1 or T1 signals via the digital transmission facility tothe central office. TR-008 basically adopts a fixed time slot allocationscheme between the switch and the RDT.

Over the recent years, the switch and the RDT based on TR-303 or GR-303as a standard substitute for TR-008 has been spreading (the RDT based onTR/GR-303 will hereinafter be referred to as a “TR/GR-303RDT” as thecase may be) for the purposes of efficiently utilizing transmission pathbandwidth, doing a standardized operation and management and expandingthe subscribers.

The TR/GR-303RDT allocates (time slot allocation) 2048telephone lines atthe maximum to 28 lines of DSX-1 or T1 signals (DS1) at the maximum by aline concentration function. A main target of the service provided bythis TR/GR-303RDT is a voice service. Architecture of the network towhich the TR/GR-303RDT is applied is much the same as architecture ofthe network to which the TR-008RDT is applied.

By the way, there has recently increased a demand for data (packet)communications on the Internet, and a remote digital terminal called anintegrated access device (IAD) is developed. The integrated accessdevice is a small capacity (one DSX-1 or T1 at the minimum, i.e., 24DS0s at the minimum) type remote digital terminal that receives data andconventional telephone services.

The integrated access device is generally installed in a small businessoffice steering clear of installing a large capacity device butrequiring a predetermined or wider transmission bandwidth. All theintegrated access devices support TR-008 as a switch interface.

TR-303 was developed for the purpose of accommodating a multiplicity ofsubscribers, and hence, if the device implements TR-303, it is requiredthat large-scale and complicated hardware and firmware be incorporatedtherein. By contrast, an implementation of TR-008 can be actualized bysmall-scale and simple hardware for firmware.

The integrated access device has only architecture for accommodatingtelephone (including modem) and ISDN subscribers that implement TR-008,and for connecting these subscribers to the switch supporting TR-008.Namely, the integrated access device supports only TR-008. Therefore, asshown in FIG. 11B, it was unfeasible to provide the service from theswitch to the telephones and others by mutually connecting to the switchsupporting only TR/GR-303.

SUMMARY OF THE INVENTION

It is a primary object of the present invention to provide a gatewaydigital loop carrier device for executing an interface conversionbetween an integrated access device and a switch based on interfacestandards different from each other.

To accomplish the above object, according to one aspect of the presentinvention, a gateway digital loop carrier device is provided between aswitch and an integrated access device that has interfaces differentfrom each other, executes an interface conversion for connecting theswitch and the integrated access device to each other.

According to the present invention, the switch and the integrated accessdevice can be connected to each other by executing the interfaceconversion. This architecture enables the subscribers accommodated inthe integrated access device to utilize the services from the switchwith supports the different interface.

According to the present invention, the gateway digital loop carrierdevice may accommodate the integrated access device accommodating as asubscriber at least one of a telephone, a modem and ISDN andimplementing a TR-008 interface, and may connect the subscriber to theswitch implementing a TR-303 or GR-303 interface.

The gateway digital loop carrier device according to the presentinvention may further comprise a signaling converting unit forconverting a subscriber line (signaling) system between TR-008 andTR-303 or GR-303.

The gateway digital loop carrier device according to the presentinvention may further comprise an ISDN overhead converting unit forconverting a protocol of overhead information on an ISDN D+ (plus)channel between TR-008 and TR-303 or GR-303.

The gateway digital loop carrier device according to the presentinvention may further comprise a trouble detecting unit for detecting atrouble on a transmission path between the integrated access device andthe gateway digital loop carrier device, and a service state informationconverting unit for converting the detected trouble into subscriberservice state information of which the switch is notified, wherein theswitch may be notified of the subscriber service state information tostop billing.

In the gateway digital loop carrier device according to the presentinvention, the switch and the integrated access device can be connectedto each other by executing the interface conversion between theintegrated access device and the switch that are based on the interfacestandards different from each other, whereby the subscribersaccommodated in the integrated access device are able to utilize theservices from the switch.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a TR-008 signaling table in a POTS service; FIG. 1B is aTR-303 signaling table in the POTS service;

FIG. 2 is a diagram showing an embodiment of a gateway digital loopcarrier device according to the present invention;

FIGS. 3A and 3B are tables showing mappings in a Robbed Bit Signalingconversion;

FIGS. 4A and 4B are tables showing mappings in the Robbed Bit Signalingconversion;

FIG. 5 is a table showing mappings between a CMISE service and an ISDNprotocol conversion;

FIGS. 6A and 6B are tables showing mappings (ISDN FPT) between the CMISEservice and the ISDN protocol conversion;

FIG. 7 is a table showing mappings (ISDN FPT) between CMISE attributesand the ISDN protocol conversion;

FIG. 8 is a table showing mappings (ISDN FPT) between the CMISEattributes and the ISDN protocol conversion;

FIG. 9 is a diagram showing a specific example of the embodimentillustrated in FIG. 2;

FIG. 10 is a diagram showing a specific example of the embodimentillustrated in FIG. 2; and

FIGS. 11A and 11B are explanatory diagrams showing prior arts.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[Details of the Present Invention]

An integrated access device (IAD) is a device for providing voiceservices and data services on one single platform by utilizing an XDSL(x Digital Subscriber Line) technology that is recently going to spread.The integrated access device is installed mainly in a small office. Theintegrated access device generally supports TR-008 with respect to thevoice services.

TR-008 is an old type system in the public line network, however,hardware and firmware thereof are small in size and simple. Theintegrated access device has large requirements such as downsizing ofthe device and a reduction in cost, and it is therefore optimal to adoptTR-008.

Over the recent years, the public line network has shifted to TR/GR-303from TR-008. This is conspicuous particularly in newly-risen telephonecompanies known as CLECs (Competitive Local Exchange Carriers). Theintegrated access device supports TR-008 but does not support TR/GR-303.This type of integrated access device is incapable of connectingdirectly to the public line network (switch) adopting TR/GR-303.

The following is a presumption of the reason why the integrated accessdevice does not support TR/GR-303. Originally, the integrated accessdevice deals with the voice service as [something extra], and must avoida rise in cost and a scale-up of the device due to the voice service.Further, the integrated access device is constructed for the purpose ofaccommodating several subscribers.

By contrast, TR/GR-303 cancels out the scale-up and complication of thehardware and firmware by accommodating a large quantity of subscribers(over 2000) (a cost per subscriber is reduced).

It is therefore improper that the integrated access device incorporatesthe hardware and firmware supporting TR/GR-303. This is because, ifincorporated, the scale-up and the rise in cost are brought about. Thevoice service may be conceived as [extra] to the integrated accessdevice but is still as important to an end user as before in the publicline network.

On the other hand, if the integrated access device does not supportTR/GR-303, it can be considered that the remote digital terminal(TR/GR-303RDT) supporting TR/GR-303 is introduced.

The installer of the integrated access device is, however the smalloffice. Hence, it cannot be assumed that the small office installs theTR/GR-303RDT becoming optimal in terms of a cost performance byaccommodating 2000 or more subscribers. It can be presumed from what hasbeen explained so far that there continues a state where the voiceservice subscribers embraced by the integrated access device remainunable to connect directly with the TR-303 public line network.

Next, a difference between TR-008 and TR-303 will be explained in depth.The integrated access device (TR-008IAD) supporting TR-008 is physicallyconnectable to a switch (TR-303 switch) that supports TR-303.

Both of the integrated access device (TR-008) and the switch (TR-303),however, must involve the use of DS1 for a transmission signalinterface, and DS1 must be divided into DS0s. Even if both of theintegrated access device and the switch are physically connectable,however, the normal service cannot be provided. It is because TR-008 andTR-3-3 have the following crucial differences (1)˜(3).

(1) Subscriber Line Signaling

Signaling is defined as a system for notifying the switch of a state ofa telephone (such as on-hook/off-hook) and dial information. The switch,when directly accommodating the telephone lines, monitors whether thetelephone lines (two wires in the case of an ordinary telephone service)forma loop and this loop opens (this shows a signaling system calledLoop Start, and the way of how the switch monitors the telephone linesdepends on the signaling system). This signaling system enables theswitch to know the state of the telephone.

By contrast, if the remote digital terminal or the integrated accessdevice is interposed between the telephone and the switch, the switch isincapable of directly accommodating the telephone lines. It is thereforerequired that the switch be informed of telephone state by signalingfrom the remote digital terminal or the integrated access device.

Herein, TR-008 adopts such a system (known as “Robbed Bit Signaling”)that a signaling bit is allocated to a predetermined bit of DS0 (thesignaling bit overwrites a voice data in the DS0). In this respect,TR-008 and TR-303 are the same.

TR-008, however, defines 2 bits of “A” and “B” at a 1.5 ms [millisecond]cycle by way of Robbed Bit Signaling. On the other hand, TR-303 defines4 bits of “A”, “B”, “C” and “D” at a 3 ms [milli second] cycle by way ofRobbed Bit Signaling. Namely, TR-008 can express only four states with 2bits. In contrast with TR-008, TR-303 expresses 16 states with 4 bits.

TR-303 is a standard created later than TR-008, and a function of TR-303is extended so that a larger number of states than by TR-008 can beexpressed. This implies that if TR-303 is converted into TR-008, thereexist unconvertible patterns.

A most typical POTS (Plain Old Telephone Service) will herein beexemplified. POTS is identified by a signaling type called a singleparty according to TR-008. FIG. 1A shows a table of TR-008 signaling inPOTS. FIG. 1B shows a table of TR-303 signaling in POTS.

(1-1) Mutual Conversion between TR-008 and TR-303 for POTS

(A) Receiving Direction from Switch

A TR-008 channel test is a test initiation indication by a test systemconnected to the switch for maintenance and is not therefore taken intoconsideration (not used in TR-303).

As shown in FIGS. 1A and 1B, Forward Disconnect in TR-008 is a state ofbeing possible of converting into LCFO in TR-303. Further, -R Ringing inTR-008 is a state of being possible converting into -R Ringing inTR-303. Moreover, Idle in TR-008 is a state of being possible ofconverting into LCF in TR-303. By contrast, TR-008 does not have statescorresponding to DS0 AIS, DS0 RAI, and RLCF in TR-303.

(B) Transmitting Direction to Switch

As shown in FIGS. 1A and 1B, On-Hook in TR-008 is a state of beingpossible of converting into LO in TR-303. Further, Off-Hook in TR-008 isa state of being possible of converting into LC in TR-303. Stillfurther, Unequipped in TR-008 is a state of being possible of convertinginto DS0 AIS in TR-303. By contrast, TR-008 does not have a statecorresponding to DS0 RAI in TR-303.

Moreover, the signaling cycle of TR-008 is 1.5 msec, while the signalingcycle of TR-303 is 3 msec. Thus, the cycle for establishing signaling ofTR-008 is different from that of TR-303. Therefore, it is not feasibleto utilize the service via the switch simply by replacing TR-008 andTR-303 with each other.

(2) Call Control System

Call control is a system for controlling a timeslot connection (start ofservice) or disconnection (end of service) between the switch and theremote digital terminal or the integrated access device. According toTR-008, basically the timeslot is always connected.

On the other hand, according to TR-303, only when the subscriberoriginates a call (Off-Hook), the timeslot is assigned by a data linkcalled TMC. This scheme is to effectively utilize the bandwidth. Whenthe subscriber originates the call, a message named SETUP is transmittedto the switch on the data link TMC. Thereafter, the subscriber receivesa timeslot connect request (CONNECT message) from the switch, wherebythe timeslot is connected. After this connection, a signalingtransmission and receipt can be performed at DS0.

Take POTS in TR-303 for example, a problem arising herein is that thesubscriber's calling is detected by detecting a loop closure (LC) of thetelephone line, and the message SETUP is sent. In this respect, TR-303does not define a trigger for transmitting SETUP in a case where thesubscriber telephone lines are not directly accommodated as in the caseof the remote digital terminal. Accordingly, when a TR-008/TR-303conversion takes place, it is necessary to define what trigger withwhich SETUP is transmitted.

(3) Monitor/Control System

TR-008 does not particularly define monitoring and controlling exceptthat if a trouble on a transmission path is detected at a receiving end,a notification thereof (called a [remote alarm indication] is sent on aDS1 (SLC96) data link.

On the other hand, TR-303 defines monitoring and controlling whichinvolve the use of a data link called EOC. A TR-303EOC basedmonitoring/controlling system is defined in CMISE information modeprescribed by TR-303 supplement 3.

According to this definition, the TR-303EOC based monitoring/controllingsystem is actualized by mapping a physical resource (e.g., a telephoneline) of the remote digital terminal to an abstract model known as amanaged object, and executing a variety of operations with respect tothis abstract model.

On the occasion of executing the TR-008/TR-303 conversion, what is mostdifficult is a conversion of an ISDN (Integrated Services DigitalNetwork) function. It is required that the ISDN embraced by TR-008 be,precisely, based on a different standard called TR-397.

ISDN monitoring/controlling in TR-397 is performed by a bit-orienteddata link called eoc/Indicator Bits contained in overhead informationallocated to a U-point (which is a physical interface between ISDN linecard and NT1 in a subscriber's house).

TR-303 defines isdn Line Termination and isdn Framed Path Termination asISDN managed objects, and also specifies attributes defined in thosemanaged objects and formulates operations for the managed objects.

TR-303 cannot, however, be converted directly into eoc/Indicator Bits ofTR-008 in some cases. For instance, if the ISDN U-point is given aCreate request (M-CREATE) or a delete request (M-DELETE) from the TR-303switch, there is no rule of how to convert in TR-008. This is becauseTR-008 is based on the premise of being always connected and thereforehas no concepts of Create and Delete. Create implies a start of theservice, while Delete implies a stop of the service. If deleted,accounting is stopped, and therefore something must be done.

Further, among the attributes specified by TR-303, some attributes arenot specified by TR-008. For example, these attributes are primaryService State, secondary Service State, and channel Selection. There isno rule of how to convert these attributes on TR-008.

Moreover, if U-point performance monitoring data are collected by TR-008(T-397 eoc), it takes much time. Hence, a performance problem arises ifTR-303 is simply converted into TR-008.

On the other hand, if a trouble occurs on the transmission path betweenthe remote digital terminal and the integrated access device in casesother than ISDN, there is a problem of how to make it appear to be theswitch. TR-303 is based on the premise of directly accommodating thetelephone lines. Therefore, TR-303 has no rule of how to notify (whichmanaged object and with what attribute) if a trouble occurs in DS1 whenaccommodating the telephone lines not directly but in the form of DS0 onDS1. If the trouble occurs in DS1, an influence is exerted on the callcontrol (i.e., the service), and hence something must be done.

[Embodiments of the Present Invention]

FIG. 2 is a diagram showing an embodiment of a gateway digital loopcarrier device 100 of the present invention. The gateway digital loopcarrier device 100 is provided between an integrated access device(TR-008IAD) 110 based on TR-008 and a switch (TR/GR-303 switch) 120based on TR/GR-303, and is connected the device 110 and the switch 120via communication lines.

The gateway digital loop carrier device 100 includes, an IADtransmission signal terminating unit A, a DS0demultiplexing/multiplexing unit B connected to the IAD transmissionsignal terminating unit A, a signaling conversion unit C connected tothe DS0 demultiplexing/multiplexing unit B, and a subscriber connectionunit D connected to the DS0 demultiplexing/multiplexing unit B and tothe signaling conversion unit C. The gateway digital loop carrier device100 further includes a TR-303RDT unit E connected to the subscriberconnection unit D, a switch transmission signal terminating unit Fconnected to the TR-303RDT unit E, an ISDNOH terminating unit Gconnected to the DS0 demultiplexing/multiplexing unit B and EOCconverting unit H, and an EOC converting unit H connected to the IADtransmission signal terminating unit A and to the ISDNOH terminatingunit G. The EOC converting unit His connected to the IAD transmissionsignal-terminating unit A. The switch transmission signal terminatingunit F is connected to a switch 120 via a communication line.

The IAD transmission signal terminating unit A terminates thetransmission signal between the integrated access device 110 and thegateway digital loop carrier device 100. The IAD transmission signalterminating unit A has a transmission signal interface such as SONET,DS3, T1 and so on, and eventually terminates DS1.

The IAD transmission signal terminating unit A detects a trouble on thetransmission path between the integrated access device 110 and thegateway digital loop carrier device 100. Further, the IAD transmissionsignal terminating unit A terminates the DS1 data link. Moreover, theIAD transmission signal terminating unit A extracts Robbed Bit Signalinginformation of TR-008 per DS0 from the DS1 signals terminated.

The DS0 demultiplexing/multiplexing unit B demultiplexes DS1 terminatedby IAD transmission signal terminating unit A into a plurality (24) ofDS0s. At this time, if the demultiplexed DS0 is set by user as ISDN andits channel is D+, the DS0 demultiplexing/multiplexing unit Bdemultiplexes the D+ channel into a D channel and overhead information.

The signaling conversion unit C converts the Robbed Bit Signalinginformation per DS0 which has been extracted by the IAD transmissionsignal terminating unit A into Robbed Bit Signaling information ofTR-303. This signaling conversion process involves the use of signalingtype and a line type per DS0 that are set by the user. Namely, thesignaling conversion process is enabled only in a case where the linetype is analog, and the way of how the extracted Robbed Bit Signalinginformation is converted, depends on the signaling type. The signalingconversion process will be described later on. The converted Robbed BitSignaling information is inserted to DS0 corresponding thereto.

The subscriber connection unit D receives the plurality of demultiplexedDS0s from the DS0 demultiplexing/multiplexing unit B, and determineswhich port among a plurality of subscriber ports (CRVs: Call referenceValues) possessed by the TR-303RDT unit E receives a connection of eachDS0. Namely, the subscriber connection unit D specifies a CRV numberallocated to each DS0. The user sets which CRV each DS0 is connected to.

The TR-303RDT unit E performs the call control andmonitoring/controlling based on TR/GR-303 with respect to DS0 with theCRV number between switch and the RDT. The TR-303RDT unit E executes thecall control through a TMC data link and also a process of connectingCRV specified by the switch to DS1/DS0 specified. Themonitoring/controlling is carried out through an EOC data link.

The switch transmission signal terminating unit F implements a functionof terminating the transmission signal between the gateway digital loopcarrier device 100 and the switch 120. The switch transmission signalterminating unit F performs framing of 24 lines of DS0s outputted fromthe TR-303RDT unit E into DS1, and thereafter multiplexes DS1 into atransmission signal interface (e.g., SONET) required.

The ISDN OH terminating unit (ISDN overhead terminating unit) Gterminates ISDN overhead information extracted by the DS0demultiplexing/multiplexing unit B, and extracts eoc/Indicator Bitscontained in the overhead information. Note that the ISDN overheadterminating unit G inserts eoc/Indicator Bits with respect to adownstream direction (a receiving direction from the switch 120).

The EOC converting unit H interprets and generates an EOC message sentfrom the switch 120, and manages information needed for interpreting andgenerating the EOC message. The EOC converting unit D manages thetransmission path trouble information detected by the IAD transmissionsignal terminating unit A as service state information of CRV specifiedby the subscriber connection unit D. The switch 120 is notified of theservice state information based on CRV number.

Further, the EOC converting unit H manages Indicator Bits extracted bythe ISDN overhead terminating unit G as state-of-overhead (NT1 terminaland subscriber line) information in a network direction (a direction oftransmission to the switch 120) with respect to ISDN CRV. The switch 120is notified of the state-of-overhead information. Eoc is used mainly formaintenance from the switch. The EOC converting unit H interprets theEOC message received from the switch 120 and converts it into eoc.

<Signaling Conversion>

The signaling converting unit C executes a signaling conversion(TR-008/TR-303 conversion) between TR-008 and TR-303 in the followingway. To be specific, the signaling converting unit C expresses an ABpattern twice during 2 signaling cycles (3 millisecond (msec)) ofTR-008. Namely, the signaling converting unit C expresses an ABA′B′pattern. The AB pattern is a pattern of the cycle of this time, and theA′B′ pattern is a pattern of the next cycle.

Three milliseconds are coincident with a period during which an ABCDpattern of TR-303 is established. Non-coincidence of the signaling cyclebetween TR-008 and TR-303 can be thereby obviated. It is thereforefeasible to effect a conversion (a downstream direction) into the ABpattern from the ABCD pattern and a conversion (an upstream direction)into the ABCD pattern from the AB pattern.

According to this, a signaling state (code) after the conversion is notestablished unless 3 msec have elapsed immediately after the start ofthe system operation in both of transmitting and receiving to and fromthe switch 120. TR-303, however, uses the call control in a lineconcentration system. Namely, in TR-303, the timeslot is in normally inan unconnected state, and signaling does not become transparent betweenthe switch 120 and the gateway digital loop carrier device 100. Hence,no problem arises as for 3 msec delay described above. If the signalingstate after the conversion is established, the signaling conversion canbe done without any delay from its establishment onwards.

An unconvertible pattern, i.e., a TR-303 based signaling state (code)not defined by TR-008 is converted into a TR-008 code that received atleast no influence by this conversion, or alternatively the TR-303 codeis substantially ignored.

A case where the signaling type is POTS will be exemplified. If POTScodes received from the switch 120 are DS0 AIS and RLCF, the signalingconverting unit C converts these codes into a TR-008 Idle where at leastno influence occurs due to this conversion.

By contrast, if the POTS code is DS0 RAI, the signaling converting unitC substantially ignores this code, and sends the code one cycle beforewithout executing the converting process. Therefore, the signalingconverting unit C stores the code one cycle before.

On the other hand, when the signaling (code) is transmitted to theswitch 120, the signaling converting unit C, if the conversion targetsignaling (code) is a code undefined by TR-008, does not convert thiscode and sends the code one cycle before.

Further, when transmitting DS0 RAI to the switch 120, the signalingconverting unit C, just when receiving DS0 AIS from the switch 120,overwrites the signaling directed to the switch 120 to the code DS0 RAI.

FIGS. 3A, 3B, 4A and 4B show specific conversion tables each showing theTR-008/TR-303 conversion corresponding to each of a plurality ofservices including POTS. FIGS. 3A and 3B show the conversion tables (ofthe ABCD-to-AB pattern conversion) in the case of transmitting thesignaling in the downstream direction(the switch 120→the integratedaccess device 110). FIGS. 4A and 4B show the conversion tables (of theAB-to-ABCD pattern conversion) in the case of transmitting the signalingin the upstream direction (the integrated access device 110

the switch 120).

The signaling converting unit C converts the signaling state (code) inaccordance with the conversion tables shown in FIGS. 3A, 3B, 4A and 4B,and outputs the converted code. The outputted code (bit string) isoverwritten to DS0 corresponding thereto.

<Call Control System Conversion>

The TR-303RDT unit E deals with DS0 the same as the telephone linedirectly accommodated by the gateway digital loop carrier device 100 inorder to obviate a difference in call control system between TR-008 andTR-303. That is, TR-303RDT unit E refers to the signaling state (code)corresponding to DS0 in the upstream direction from the subscriberconnection unit D, and, if this code is a pattern representing anOff-Hook state, treats this code as calling from the subscriber. Then,the TR-303RDT unit E sends SETUP onto TMC.

Thus, the TR-303RDT unit E sends SETUP to the switch 120, which istriggered by detecting the signaling of the Off-Hook pattern, andconnects the time slot between the gateway digital loop carrier device100 and the switch 120. A signaling pattern to trigger sending SETUP forevery signaling type is a signaling pattern corresponding to “0”indicated by *2 in FIGS. 4A and 4B. Take POTS for instance, if thesignaling pattern (code) after the conversion is “1111”, SETUP istransmitted.

<Monitoring/Controlling System Conversion>

FIGS. 5 and 6 are tables each showing an ISDN protocol convertingprocess for an ISDN service (CMISE Service) that can not be converteddirectly into eoc/Indicator Bits of TR-008. FIGS. 7 and 8 are tableseach showing an ISDN protocol converting process with respect to CMISEAttribute undefined by TR-008. The EOC converting unit H executes theISDN protocol converting process shown in FIGS. 5, 6A, 6B, 7 and 8.

The EOC converting unit H, in the ISDN protocol converting process, doesnot collect all categories of performance monitoring data (34categories) with eoc but collects only Current Count (10 categories),and accumulates Current Count on the side of the gateway digital loopcarrier device with respect to Previous and History Count (see FIGS. 7and 8). A time for collecting the U-point performance monitoring data isthereby reduced.

<Specific Examples>

FIG. 9 is a diagram showing an example of the operation of a gatewaydigital loop carrier device 200 by way of a specific example of thegateway digital loop carrier device 100 shown in FIG. 2. FIG. 10 is adiagram showing an example of architecture of the gateway digital loopcarrier device 200 shown in FIG. 9.

The gateway digital loop carrier device 200 accommodates an integratedaccess device (TR-008IAD) 110 that accommodates a telephone (POTS/PBX),a modem (MODEM), a data terminal and ISDN. The gateway digital loopcarrier device 200 is connected to a local switch (TR-303 switch) 120for providing the voice services via a SONET LINE and to DCS (DigitalCross connect System) 121 for providing data services.

The gateway digital loop carrier device 200 includes a TR-303/TR-008interface converting unit, a TR-303RDT unit and a SONET multiplexer(SONET multiplexing unit) so that voice subscribers (POTS/PBX, ISDN)accommodated in the integrated access device 110 receive the servicesfrom the TR-303 switch 120.

To be specific, the gateway digital loop carrier device 200 includes aplurality of SONET multiplexing units 1, a VT1.5 cross connectunit/VT1.5 path terminating unit 2, a plurality of DS1 line terminatingunits 3, and a selector 4 connected to the DS1 line terminating unit 3.The gateway digital loop carrier device 200 further includes a DS1 pathterminating unit 5 connected to the selector 4, a DS0demultiplexing/multiplexing unit 6 connected to the DS1 path terminatingunit 5, an ISDN overhead terminating unit 7 connected to the DS0demultiplexing/multiplexing unit 6, a signaling converting unit 8connected to the DS0 demultiplexing/multiplexing unit 6, a subscribercross connect unit 9 connected to the DS0 demultiplexing/multiplexingunit 6, and an MPU 10 connected to the DS1 path terminating unit 5, theISDN overhead terminating unit 7 and the signaling converting unit 8.The gateway digital loop carrier device 200 still further includes aTR-303RDT unit 11 connected to the subscriber cross connect unit 9, aDS1 cross connect unit 12 connected to the TR-303RDT unit 11, and a DS1path terminating unit 13 connected to the DS1 cross connect unit 12 andalso connect to the VT1.5 cross connect unit/VT1.5 path terminating unit2.

Each of the SONET multiplexing units 1,in the downstream direction,terminates OC-3 or OC-12 signals (of a switch 120 type) on the networkside, then demultiplexes the OC-3 or OC-12 signals into a plurality ofVT1.5 paths (84 lines o VT1.5 signals), and sends the demultiplexedsignals to the VT1.5 cross connect unit/VT1.5 path terminating unit 2.

On the other hand, each of the SONET multiplexing units 1, in theupstream direction, generates the OC-3 or OC-12 signals by multiplexingthe plurality of VT1.5 paths, and sends the thus generated signals tothe network. Referring to FIG. 9, #1, #2 given to the respective SONETmultiplexing unit 1 represent optical interfaces when the SONET linesconfigure UPSR rings.

The VT1.5 path terminating unit/VT1.5 cross connect unit 2, in thedownstream direction, terminates a VT1.5 path extending from the switch120, then demultiplexes it into a bundle of VT1.5 signals (28/56 linesof VT1.5 signals), and transmits these signals to the selector 4 or theDS1 path terminating unit 13 along these outgoing paths. On the otherhand, the VT1.5 path terminating unit/VT1.5 cross connect unit 2, in theupstream direction, generates a VT1.5 path that multiplexes 28/56 linesof VT1.5, and transmits these signals to the SONET multiplexing unit 1corresponding to the outgoing paths.

The DS1 line terminating unit 3 has a DS-1 or T1 signal interface and,in the upstream direction, terminates the transmission signals betweenthe gateway digital loop carrier device 200 and the integrated accessdevice 110.

The selector 4 executes any one of the following items with respect tothe DS1 signals terminated by the DS1 line terminating unit 3 inaccordance with the setting by the user.

(a) Connection to the VT1.5 cross connect unit/VT1.5 path terminatingunit 2;

(b) Connection to the DS1 path terminating unit 5; and

(c) Non-connection (initial value).

The transmission signals inputted to the gateway digital loop carrierdevice 200 from the integrated access device 110 are of one type of thedata signals (that can be neither divided into DS0s nor accommodated inthe switch 120) and the voice signals (that can be divided into DS0s andaccommodated in the switch).

The selector 4, if the transmission signals are the data signals,connects the data signals to the VT1.5 cross connect unit/VT1.5 pathterminating unit 2, and, if the transmission signals are the voicesignals, connects these signals to the DS1 path terminating unit 5 inaccordance with the setting by the user.

Further, if the DS1 is not yet used (if not yet connected to theintegrated access device 110), the user setting for the selector 4 isdone via the MPU 10. The broken line drawn in the selector 4 shown inFIG. 9 indicates an example of connection of the data signals, and thesolid line indicates an example of connection of the voice signals.

The DS1 path terminating unit 5 terminates the DS1 path between thegateway digital loop carrier device 200 and the integrated access device110, and outputs a plurality of DS0s in the DS1 path to the DS0demultiplexing/multiplexing unit 6. The DS1 path terminating unit 5detects a trouble on the DS1 Line/Path, terminates the DS1 data link,detects a remote alarm to the DS1 data link, and extracts Robbed BitSignaling. Extracted Robbed Bit Signaling is outputted together with DS0to the DS0 demultiplexing/multiplexing unit 6. This DS1 path terminatingunit 5 corresponds to the IAD transmission signal terminating unit Ashown in FIG. 2, and corresponds to a terminating unit on the side ofthe integrated access device of the present invention.

The DS0 demultiplexing/multiplexing unit 6 demultiplexes DS1 into aplurality of DS0s. Further, the DS0 demultiplexing/multiplexing unit 6extracts Robbed Bit Signaling contained in DS0s. Moreover, the DS0demultiplexing/multiplexing unit 6 terminates the ISDN D+ channel. ThisDS0 demultiplexing/multiplexing unit 6 corresponds to the DS0demultiplexing/multiplexing unit B shown in FIG. 2, and corresponds to ademultiplexing unit of the present invention.

The ISDN overhead terminating unit 7 extracts eoc/Indicator Bits fromthe D+ cannel terminated by the DS0 demultiplexing/multiplexing unit 6,and notifies the MPU 10 of eoc/Indicator Bits. The user sets a line typeand a channel type needed for this process in the ISDN overheadterminating unit 7 through the MPU 10. This ISDN overhead terminatingunit 7 corresponds to the ISDN overhead terminating unit G shown in FIG.2.

The signaling converting unit 8 converts TR-008 Robbed Bit Signalinginputted from the DS0 demultiplexing/multiplexing unit 6 into TR-303Robbed Bit Signaling in accordance with the conversion table shown inFIG. 4, and outputs the converted signaling again to the DS0demultiplexing/multiplexing unit 6. On the other hand, the signalingconverting unit 8 converts the TR-303 Robbed Bit Signaling inputted fromthe DS0 demultiplexing/multiplexing unit 6 into TR-008 Robbed BitSignaling in accordance with the conversion table shown in FIGS. 3A and3B, and outputs the converted signaling again to the DS0demultiplexing/multiplexing unit 6. The line type and a signaling typerequired for the signaling conversion are set by the user through theMPU 10. The signaling converting unit 8 corresponds to the signalingconverting unit C shown in FIG. 2.

The subscriber cross connect unit 9 has a FROM-side end point and aTO-side end point. The FROM-side end point is a switch-side end point,and the TO-side end point is a subscribed-side end point. In thisembodiment, the TO-side end point selects anyone of the following items:

(a) Subscriber accommodated directly by the gateway digital loop carrierdevice 200;

(b) DS0 subscriber accommodated by the integrated access device 110; and

(c) Non-connection (initial value).

A connection of the dotted line drawn in the subscriber cross connectunit 9 in FIG. 9 is an example of connecting the subscriber line (copperline) accommodated directly by the gateway digital loop carrier device200 to predetermined CRV of the TR-303RDT unit 11. By contrast, aconnection of the solid line drawn in the subscriber cross connect unit9 is an example of connecting the subscriber line (DS0) accommodated bythe integrated access device 110 to predetermined CRV. The user setsthrough the MPU 10 which subscriber line and which CRV are connected toeach other. This subscriber cross connect unit 9 corresponds to thesubscriber connection unit D shown in FIG. 2.

The MPU 10 is defined as firmware configured by one or moremicroprocessor(s). The MPU 10 provides at least one of an RS-232 localport (to which the data terminal is connected), an RS-232C modem port(to which the modem is connected), and RS-485 port, a 10BASE-T port (towhich LCN (LAN for monitoring device) is connected) and SONET DCC forremote control, as a user interface for the user of the gateway digitalloop carrier device 200 to set and inquire about a device state, andaccepts the settings from the user therethrough.

The user sets through the user interface on the MPU 10 a line type, asignaling type, an ISDN overhead protocol conversion (setting for a D+channel) and make a setting with respect to a trouble on thetransmission path and settings for the selector 4 and the subscribercross connect unit 9. The user can make the variety of settings by useof, e.g., TL-1 (Transaction Language 1) provided as a user interface onthe MPU 10.

The user settings are terminated within the gateway digital loop carrierdevice 200 and are distributed to neither the integrated access device110 nor the switch 120. The user settings necessary for the face-to-facedisposed devices (the integrated access device 110 and the switch 120)can be made independently of each other.

Further, the MPU 10 analyzes and generates an EOC/TMC message withrespect to the switch 120 in accordance with the user settings. The MPU10 also executes control and state collection within the gateway digitalloop carrier device 200 and the call control of the data link TMC. ThisMPU 10 corresponds to the EOC converting unit H shown in FIG. 2.

The TR-303RDT unit 11 carries out a timeslot connection anddisconnection based on the TMC call control for the connectedsubscriber. In this embodiment, four pieces of TR-303RDT units 11 areprovided and actualized by the dynamic cross connects accommodating 2016subscribers (having 2016 CRVs) at the maximum on the subscriber (TO)side and 672 DS0s at the maximum on the switch (FROM) side.

Further, the TR-303RDT unit 11 terminates a data link EOC/TMC andexecutes monitoring and controlling via the data link EOC. ThisTR-303RDT unit 11 corresponds to the TR-303RDT unit E shown in FIG. 2,and corresponds to a call control unit of the present invention.

The DS1 cross connect unit 12 maps, to any one VT1.5 on SONET, 24 DS0sfor every TR-303RDT, which are outputted from the TR-303RDT unit 11.This arrangement schemes to obtain mappings between DS1 logical linesand SONET physical lines.

The DS1 path terminating unit 13 terminates a DS1 path. The DS1 pathterminating unit 13 corresponds to the switch transmission signalterminating unit F shown in FIG. 2.

<User Settings>

In this embodiment, the user settings are actualized by the followingTL-1 commands via the user interface provided on the MPU 10.

(Setting 1) Setting of Selector 4

Syntax: ED-VT1:<TID>:<AID>:<CTAG>:::<<KEYWORD=DOMAIN>>:;RTRV-VT1:<TID>:<AID>:<CTAG>:::, TID:This is defined as an ASCII character string representing a name of thetarget gateway digital loop carrier device 200.AID:This is defined as a piece of identifying information of the physicaltransmission path between the target integrated access devices 110, andis expressed in a format such as <LG#>-<VTG#>-<VT#>, where <LG#>={4,5}indicates a slot position, and <VTG#>={1 . . . 7}, <VT#>={1 . . . 4}indicates a DS1 position at the slot concerned.KEYWORD=DOMAIN:This command indicates a setting item and a set value with respect tothe physical transmission path. The setting item and the set valueprovided by this command are TYPE and DDL that follow.TYPE={DS0, DS1, NONE} is used for the setting of the selector 4. Theuser specifies DS0 if the transmission signal carries the voice signal,DS1 if carrying the data signal and NONE (unconnected) if unused.DDL={YES, NO} indicates whether or not the transmission signal carriesthe data link. The user specifies YES if the transmission signal uses anSLC-96 frame format and on an A-line, and specifies NO if other thanthis case.

Note that the user is able to refer to the settings with the RTRV-VTLcommands.

(Setting 2) Setting of Line Category

Syntax: ENT-TO:<TID>:<AID>:<CTAG>:::<<KEYWORD=DOMAIN>>:;ED-TO:<TID>:<AID>:<CTAG>::: <<KEYWORD=DOMAIN>>:;DLT-TO:<TID>:<AID>:<CTAG>:::; RTRV-TO:<TID>:<AID>:<CTAG>:::; TID:This is defined as an ASCII character string representing a name of thetarget gateway digital loop carrier device.AID:This is an identifier of DS0 between the target integrated accessdevices and is expressed in a format such as <LG#>-<VTG#>-<VT#>-<DS0#>,where <LG#>, <VTG#> and <VT#> are the same as those in (Setting 1)described above and indicate DS0 positions on DS1 concerned with<DS0#>={1 . . . 24}KEYWORD=DOMAIN:This command indicates a setting item and a set value with respect toDS0. The setting item and the set value provided by this command are:GSFN={SINGLE-PARTY, UVG-LS, UVG-GS, COIN-DTF, COIN-CF, ANI2, DID-DPT,DID-DPO, FXO-LS, FXO-GS, FXS-LS, FXS-GS, TDM-FXS, TDM-FXO, TDME&M, DX,E&M, PLR, ISDN, DDS}In the case of the line type is the analog line, the signaling type isspecified. FIGS. 3 and 4 show mappings between the set values, the linetypes and the signaling types.When CFA={ONHK, OFFHK, EBSY} and trunk-conditioning, an ENT-TO or ED-TOcommand is used for setting what state the subscriber line is set in.The ENT-TO command sets concerned DS0 in an in-service state, and theED-TO command keeps the service state with only a change in setting. ADLT-TO command is used for setting in an out-of-service state. AnRTRV-TO command refers to the setting state.(Setting 3) Subscriber Cross Connect to TR-303RDT Unit 11 andIdentification of ISDN D+ Channel

Syntax: ENT-CRS-TO:<TID>:<FROMAID>:<TOAID>:<CTAG>:::;DLT-CRS-TO:<TID>:<FROMAID>:<TOAID>:<CTAG>:::;RTRV-CRS-TO:<TID>:<FROMAID>:<TOAID>:<CTAG>:::; TID:This is defined as an ACSII character string indicating a name of thetarget gateway digital loop carrier device.FROMAID:This indicates CRV of the TR-303RDT unit 11 and is expressed in a formatsuch as RDT303-<IG#>-<CRV#>-<CH TYPE>, WHERE <IG#>={1 . . . 4} indicatesa serial number of the TR-303RDT unit 11, and<CRV#>={1 . . . 2016}indicates CRV (a subscriber identification number corresponding to atelephone number) of an arbitrary TR-303RDT unit 11. A line type of DS0specified by TOAID is effective in the case of only ISDN/DDS with <CHTYPE>={B1/B2/D/P/S}.TOAID:This is a piece of information for specifying DS0 of the integratedaccess device 110 to be accommodated and is expressed in a format suchas <LG#>-<VTG#>-<VT#>-<DS0#>, where <LG#>, <VTG#>, <VT#>, <DS0#> are thesame as those in (Setting 2) described above.The connection is established by an ENT-CRS-TO command. A DLT-CRS-TOcommand disconnects a specified connection. An RTRV-CRS-TO commandrefers to a connection state.

<EOC Conversion>

The following is a corresponding relation with the information model(Managed Object and Service contaminant therewith) prescribed by TR-303Supplement 3.

(1) Trouble on Transmission Path between Integrated Access Devices 110

Managed Objects affected when a trouble occurs on the transmission pathand when recovered, are analog Line Termination and isdn LineTermination. These Managed Objects have Attributes (corresponding tosubscriber service state information) termed primary Service State andsecondary Service State, and are set to primary Service State={oos},secondary Service State={mt,fef} when the trouble occurs. By contrast,when recovered from the trouble, the Managed Objects are set to primaryService State={is}, secondary Service State={} (empty).

Namely, each DS1 path terminating unit 5 monitors the transmission pathbetween the integrated access device 110 and the gateway digital loopcarrier device 200, and detects the trouble on this transmission path.Alternatively, the DS1 path terminating unit 5 receives via the datalink the trouble information on the transmission path of which thetrouble is detected in the face-to-face disposed device (the integratedaccess device 110).

When the DS1 path terminating unit 5 detects the transmission pathtrouble, the MPU 10 voluntarily sets to OUT OF SERVICE (stop ofservice), a service state (CRV of the TR-303RDT unit 11 corresponding tothe transmission path with the trouble occurred) of the subscriber,which is carried on the transmission signal on the transmission pathwhere the trouble occurred. In contrast with this, when the DS1 pathterminating unit 5 detects a recovery from the transmission pathtrouble, the MPU 10 sets to IN SERVICE (during the service) a servicestate of CRV corresponding to the recovered transmission path.

These Attributes can be referred to with M-GET from the switch 120. Onthe other hand, the TR-303RDT unit 11 of the gateway digital loopcarrier device 200 notifies the switch 120 of a change in the servicestate of CRV by use of M-EVENT-REPORT.

(2) ISDN Overhead Protocol Conversion

Managed Objects affected are isdn Line Termination and isdn Frame PathTermination. FIGS. 5, 6 and 7 show mappings between the protocolconversions and Managed Objects.

Namely, eoc/Indicator Bits extracted by the ISDN overhead terminatingunit 7 are transferred to the MPU 10. The MPU 10 converts eoc/IndicatorBits received into an EOC message corresponding thereto. The TR-303RDTunit 11 notifies the switch 120 of the EOC message obtained by thisconversion via the data link EOC.

Note that the discussion in this embodiment has been focused on theinterface conversion between TR-008 and TR-303, however, the gatewaydigital loop carrier device 200 in this embodiment can be alsoconfigured as a device for executing the interface conversion. Theconfiguration in this case is substantially the same as that in theembodiment described above.

According to the embodiment, the subscribers accommodated in theintegrated access device 110 having only the TR-008 interface, areaccommodated in the TR/GR-303 switch 120, whereby the service can beprovided.

Further, the gateway digital loop carrier device 200 and the integratedaccess device 110 are capable of independently operating and managingthe device and service as in the case of the user settings and so on,and hence there is no time-consuming operation of changing the hardwareand the firmware of the gateway digital loop carrier device 200 in a waythat depends upon the specifications of the integrated access device 110to be connected.

In addition, the subscribers accommodated directly in the gatewaydigital loop carrier device 200 and the subscribers accommodated in theintegrated access device 110, are able to coexist in the sameTR/GR-303RDT unit 11, whereby the subscribers can be accommodated at ahigh efficiency.

In accordance with this embodiment, it is feasible to provide thesubscribers accommodated by the different device in the TR-008 systemwith the service exhibiting the same quality as that for the subscribersaccommodated directly in the TR-303 based device.

1. A gateway digital loop carrier device comprising: an integratedaccess device side terminating unit terminating a transmission signalsent from an integrated access device accommodating as a subscriber atleast one of a telephone, a modem and ISDN and implementing a TR-008interface; a demultiplexing unit demultiplexing the terminatedtransmission signal into DS0 signals; a unit performing interfaceconversion of the demultiplexed DS0 signal from TR-008 to TR-303 orGR-303; a TR/GR-303RDT unit based on TR-303 or GR-303 and having aplurality of subscriber ports for sending the interface-converted DS0signal to a switch implementing a TR-303 or GR-303 interface; a troubledetecting unit for detecting a trouble on a transmission path betweensaid integrated access device and said gateway digital loop carrierdevice; and a service state information converting unit for convertingthe detected trouble into subscriber service state information of whichsaid switch is notified, wherein said switch is notified of thesubscriber service state information.
 2. A gateway digital loop carrierdevice according to claim 1, wherein said service state informationconverting unit, if the transmission path trouble is detected, sets in astop state a service state carried on the transmission signal to saidswitch that is transmitted on the transmission path, and said switch isnotified of the service state information indicating the service stopstate.
 3. A gateway digital loop carrier device according to claim 2,said trouble detecting unit detects a recovery from the transmissionpath trouble, said service state information converting unit, when therecovery is detected, sets in an in-service state the service statecarried on the transmission signal to said switch that is transmitted onthe recovered transmission path, and said switch is notified of thesubscriber service state information indicating the in-service state. 4.A gateway digital loop carrier device according to claim 1, wherein saidservice state information converting unit sets, to the subscriberservice state information, a service state based on the setting by theuser of said gateway digital loop carrier device.
 5. A gateway digitalloop carrier device comprising: an integrated access device sideterminating unit terminating a transmission signal sent from anintegrated access device accommodating as a subscriber at least one of atelephone, a modem and ISDN and implementing a TR-008 interface; ademultiplexing unit demultiplexing the terminated transmission signalinto DS0 signals; a unit performing interface conversion of thedemultiplexed DS0 signal from TR-008 to TR-303 or GR-303; a TR/GR-303RDTunit based on TR-303 or GR-303 and having a plurality of subscriberports for sending the interface-converted DS0 signal to a switchimplementing a TR-303 or GR-303 interface; and a subscriber crossconnect unit for connecting, to a predetermined subscriber port, the DS0signal from said integrated access device and the subscriber lineaccommodated directly in said gateway digital loop carrier device,wherein said subscriber cross connect unit connects the DS0 signal andthe subscriber line to a predetermined subscriber port on the basis ofthe setting by the user of said gateway digital loop carrier device.